Beyond the essential involvement of Rtl1 in maintaining placental fetal capillaries, the role of Rtl1 in the respiratory failure and other muscular problems observed in neonates remains unknown, although recent studies report that the ectopic expression of ovine RTL1 leads to muscle hypertrophy in mice, which mimics the sheep callipyge phenotype (Charlier et al., 2001; Fleming-Waddell et al., 2009; Byrne et al., 2010; Xu et al., 2015; Mikovic et al., 2018). The gene discussed is RTL1; the disease is respiratory failure.